redox-and-equivalent-concept-quiz-8

Redox And Equivalent Concept Quiz-8

Dear Readers,

The one subject in NEET which is candidates who can easily attain good marks is Chemistry. That's the reason, often, one doesn’t pay notice and choose to compromise it. But if one wants to rank above others, the tip is to be thorough with NEET chemistry concepts. The understanding of reactions and definite basic understanding is what requires major attention in Chemistry but once done it only gets simpler from there. The main focus on the to-do list should be on getting a hang of the NCERT syllabus of NEET chemistry..

Q1. The oxidation state of +3 for phosphorus is in:

•  Hypophosphorous acid
•  Meta-phosphoric acid
•  Ortho-phosphoric acid
•  Phosphorous acid

Solution
(d) H₃ PO₃ is phosphorous acid.  

Q2.Oxidation numbers of Fe in Fe₃ O₄ are :

•  +2 and +3
•  +1 and +2
•  +1 and +3
•  None of these

Solution

(a) Fe₃ O₄ is a mixture of FeO and Fe₂ O₃.

Q3. M is the molecular weight of KMnO₄. The equivalent weight of KMnO₄ when it is converted into K₂ MnO₄ is : 

•  M
•  M/3
•  M/5
•  M/7

Solution
(a) Mn⁷⁺+le ⟶Mn⁶⁺ ∴ E=M/1

Q4. The oxidation number of sulphur in H₂ S₂ O₈ is :

•  +2
•  +6
•  +7
•  +14

Solution
(b) Two oxygen atom have peroxide linkage, (i.e.,-1 oxidation number) and six have −2 ox.no. 

 Thus, 2 × 1+2 × a+6 × (-2)+2 × (-1)=0 

 ∴a= +6

Q5.If H₂ S is passed through an acidified K₂ Cr₂ O₇ solution, the colour of the solution :

•  Will remain unchanged
•  Will change to deep red
•  Will change to dark green
•  Will change to dark brown

Solution
  (c) Cr³⁺ ion is green; Cr₂⁶⁺+6e ⟶2Cr³⁺.  

Q6. Which quantities are conserved in all oxidation-reduction reactions?

•  Charge only
•  Mass only
•  Both charge and mass
•  Neither charge nor mass

Solution
(a) Oxidation involves loss of electrons and reduction involves gain of electrons, hence in case of oxidation-reduction reactions(redox reactions)charge remains conserved  

Q7.In a reaction 4 mole of electrons are transferred to one mole of HNO₃ when it acts as an oxidant. The possible reduction product is :

•  (1/2) mole N₂
•  (1/2) mole N₂ O
•  1 mole of NO₂
•  1 mole NH₃

Solution

(b) 4e+N⁵⁺ ⟶N⁺ ∴ Possible product is N₂ O.

Q8.The oxidation number of sulphur in S₈,S₂ F₂,H₂ S respectively are :

•  0, +1 and −2
•  +2, +1 and −2
•  0, +1 and +2
•  −2, +1 and −2

Solution
(a) S₈ has zero oxidation state of S. In S₂ F₂:2×a+2×(-1)=0; a=+1 In H₂ S:2×1+a=0; a=-2  

Q9.Saline hydrides are :

•  Strong oxidants
•  Strong reductants
•  Strong dehydrating agents
•  Strong bleaching agents

Solution

(b) 2H^-⟶H₂+2e

Q10. In the reduction of dichromate by Fe (II), the number of electrons involved per chromium atom is :

•  3
•  1
•  2
•  4

Solution

(a) Cr₂⁶⁺+6e ⟶2Cr³⁺ ;Fe²⁺⟶Fe³⁺+e